About the nrcmd Program

You can use the Web-based user interface (Web UI) or the nrcmd command line interface (CLI) to configure and manage your DNS, DHCP, and TFTP servers. This chapter describes how to use the nrcmd command line interface. It specifically describes:

•Invoking the command in batch and interactive modes

•Command organization and syntax

•Special keyboard navigation characters

Invoking the nrcmd Command

You can use the nrcmd command in batch mode by executing scripts that use the commands or by using the interactive mode in which you enter commands at the nrcmd command prompt. By default, the nrcmd command is located in C:\Program Files\Network Registrar\Local\bin on Windows and in /opt/nwreg2/local/usrbin on Solaris and Linux.

Note In Windows, if you want to run the nrcmd program from outside the installed path, you must set the CNR_HOME environment variable.

On Windows, you can invoke the nrcmd command window from the Start menu:

Start > Programs > Network Registrar 6.1 > Network Registrar 6.1 CLI

This method prompts for your user name and password. On Solaris and Linux (as well as Windows alternatively), invoke the command from the command prompt using this syntax:

cluster is the name of the machine on which the Network Registrar servers are running. If not specified, the cluster name defaults to localhost.

-Nuser

user is the Network Registrar user name.

-Ppassword

password is the password of the Network Registrar user.

-h

prints help text.

-r

logs in as a read-only user.

-bfile.txt

file.txt is the name of a file of nrcmd commands that run in batch mode; reading a line at a time and printing a new line after the prompt.

Batch Mode

The program goes into batch mode if you include a functional command or the -bfile.txt option on the line. The text file can include any number of nrcmd commands, and you can include comment lines preceded by the pound sign (#). In batch mode, you return to the normal system prompt. Note that display in batch mode is intended for parsing by an external program and, therefore, includes only command attributes that have values.

Note The last line of code in the input file must end with an end-of-line character. It is also a good practice to make the last line of code an explicit exit command.

Interactive Mode

The program goes into interactive mode if you enter just the nrmcd command, or include the cluster, user, or password options. To execute the CLI in interactive mode, enter:

nrcmd [-Ccluster] [-Nuser] [-Ppassword]

This displays the interactive nrcmd> prompt, at which you enter a functional command and any optional parameters:

nrcmd> command [parameter,parameter,...]

system-response

To enter a series of attribute values, insert commas between them. Do not add a space after the comma. If the value is a string containing one or more space characters, enclose the value in quotes:

nrcmd> zone example.com. set auth-servers=192.168.50.1,10.0.0.1

100 Ok

auth-servers=192.168.50.1,10.0.0.1

To terminate an interactive session, enter the exit command. To view the online help, enter the help command.

Registry and Environment Variables

If you omit the general options, Network Registrar gets them from the Registry or environment variables. If Network Registrar cannot find values for these parameters, it prompts you for them. If you omit the cluster name on a system where Network Registrar servers are installed, the nrcmd program assumes access to localhost and does not prompt you.

The environment variables that you can set that are recognized by the nrcmd program are CNR_NAME for the name, CNR_PASSWORD for the password, and CNR_CLUSTER for the cluster name.

Command Organization

The nrcmd commands specify a class of object, which you can create, delete, or list. Each of these objects in turn has attributes, which you can enable, disable, set, get, and unset, depending on data type. These objects may also have common methods, which are specific to the type of object, and that let you perform operations on groups of attributes.

When you use the nrcmd commands to configure Network Registrar, you manipulate:

•Classes—Things that you can create, delete, show, or list, such as scopes, policies, or zones.

–create—Creates an entry. If the entry already exists, this command returns an error.

–delete—Removes an entry.

–list—Displays all the objects of a given type, including all attributes.

–listnames—Displays only the names of all objects of a given type.

–show—Displays the values of all the attributes.

•Attributes—Things that you can enable or disable, or whose value you can set or display using these common methods:

–enable—enables a Boolean type of attribute.

–disable—disables a Boolean type of attribute.

–set—sets the value of an attribute.

–get—displays the value of an attribute.

–unset—makes an attribute have no value. You cannot unset required attributes.

As of Network Registrar 6.0, attributes that have default values are displayed in interactive mode in the form attribute = [default=value]. In interactive mode, all the attributes are displayed. In batch mode, only those attributes having values are displayed, and no default values are displayed. The display in batch mode is less user-friendly, but is more easily parsable by a program. These examples show how output compares in interactive and batch modes, respectively:

•Other custom methods—these are specific operations that you can perform on an object, beyond editing its attributes. Examples are adding a range of IP addresses to a scope, or removing hosts from a zone.

Command Usage

How you specify a series of arguments depends on the type of command you are using. The following subsections describe the differences between using the create, set, and enable commands.

Create Keyword

When you use the create keyword and there are required arguments, you must supply them. You can also supply additional arguments. You must supply the required arguments in the specified order; however, you can specify the optional arguments in any order with the syntax attribute=value.

For example, the syntax for creating a scope is:

scopenamecreateipaddress mask [attribute=value]

This means that you must supply an IP address and mask when you create a scope, and you can optionally specify other attributes of the scope.

This example creates the scope testScope with an IP address of 192.168.50.0 and a mask of 255.255.255.0:

nrcmd> scope testScope create 192.168.50.0 255.255.255.0

100 Ok

testScope:

addr = 192.168.50.0

bootp = disabled

deactivated =

...

You can also include attribute definitions on the same line. This example creates the same scope, but also specifies the name of the DNS zone to which a DHCP client's host name should be added:

After the create keyword creates and assigns all specified parameters to the object, it checks that all the required attributes have values (either default or user-specified). If you omit the required attributes, Network Registrar returns an error.

Set Keyword

You use the set keyword to set the value of an attribute that is already created. If you want to set a list of values, such as DNS servers or IP addresses, you can separate them with commas. You can also use the set keyword to set several attributes on a single line—just specify the attribute and its value followed by a space and the next attribute and value pair.

This example specifies the name of the DNS zone to which a DHCP client's host name should be added:

nrcmd> scope testScope set dns-zone-name=example.com.

100 Ok

dns-zone-name=example.com.

This example specifies the list of IP addresses for zone transfers for a zone:

nrcmd> zone example.com. set auth-servers=192.168.50.1,10.0.0.1

100 Ok

auth-servers=192.168.50.1,10.0.0.1

This example sets a client's client-class and domain name:

nrcmd> client 00:d0:ba:d3:bd:3b set client-class-name=internal

domain-name=example.com.

100 Ok

client-class-name=internal

domain-name=example.com.

The unset keyword places an attribute in the undefined state. The get keyword displays the value for an attribute.

Enable Keyword

You use the enable keyword to enable a boolean attribute. After you enable one boolean attribute, you may need to set its associated attributes. Use the disable keyword to disable a boolean attribute. You can use the unset keyword to remove the enabled or disabled state of the boolean attribute.

This example enables incremental transfer processing for the DNS server:

nrcmd> dns enable ixfr-enable

100 Ok

ixfr-enable=enabled

Once incremental transfer is enabled, this example changes its expiration interval:

nrcmd> dns set ixfr-expire-interval=10d

100 Ok

ixfr-expire-interval=1w3d

Note You cannot add set keywords to an enable command line. You need to first enable the boolean attribute, and then, on the next command line, set the associated attributes.

Attribute Flags

Command attributes are described as:

•Required—The attribute is required for the object. You must set the attribute or accept its default, and you can modify the value. You cannot use the unset keyword to set a required attribute to undefined. Trying to do so returns the error message "386 - Required attribute cannot be deleted."

•Optional—The attribute is optional and does not require a value. You can set and reset the attribute, and you can use the unset keyword to make it undefined.

•Read-only—The attribute is immutable and read-only. You can use the get keyword with the attribute, but you cannot set or unset it. Trying to set or unset a read-only attribute returns the error message "385 - Read-only attribute cannot be modified."

Saving Your Changes

The CLI waits for one of these events to occur before it saves your changes to the database:

•Invoking the save command

•Exiting from nrcmd

•Reloading a server

•Adding a resource record or host to a zone

Refreshing and Clearing the CLI Cache

The CLI caches many configuration objects that it reads. If multiple users are making changes simultaneously, one CLI instance might have cached an out of date version of an object. The session cache refresh command causes the CLI to clear its local cache of all unmodified objects, forcing it to reread objects from the configuration database. The session cache clear command forces the CLI to clear all cached data, whether or not unsaved changes were made.